f`(x)=Sin(x-b)Cos(x-a)-Sin(x-a)Cos(x-b)/Sin2(x-b)
f`(x) = Sin(x-b-x+a)/Sin2(x-b)
f`(x)=0
Sin(a-b) = 0
Therefore a-b has to be n∩ for n ε I
Hence proved
f(x)=sin(x-a)/sin(x-b)
Find prove that f(x) assumes maximum or minimum values for a-b=nπ ,n ε I
f`(x)=Sin(x-b)Cos(x-a)-Sin(x-a)Cos(x-b)/Sin2(x-b)
f`(x) = Sin(x-b-x+a)/Sin2(x-b)
f`(x)=0
Sin(a-b) = 0
Therefore a-b has to be n∩ for n ε I
Hence proved